Prevalence on beef carcasses of Mycobacterium avium subsp. paratuberculosis DNA

Pathogenic mechanisms and etiologic aspects of Mycobacterium avium subspecies paratuberculosis as an infectious cause of cutaneous melanoma

Infectious etiologies have previously been proposed as causes of both melanoma and non-melanoma skin cancer. This exploratory overview explains and presents the evidence for the hypothesis that a microorganism excreted in infected ruminant animal feces, Mycobacterium avium subspecies paratuberculosis (MAP), is the cause of some cases of cutaneous melanoma (CM). Occupational, residential, and recreational contact with MAP-contaminated feces, soil, sand, and natural bodies of water may confer a higher rate of CM. Included in our hypothesis are possible reasons for the differing rates and locations of CM in persons with white versus nonwhite skin, why CM develops underneath nails and in vulvar skin, why canine melanoma is an excellent model for human melanoma, and why the Bacille Calmette-Guérin (BCG) vaccine has demonstrated efficacy in the prevention and treatment of CM. The pathogenic mechanisms and etiologic aspects of MAP, as a transmittable agent underlying CM risk, are carefully deliberated in this paper. Imbalances in gut and skin bacteria, genetic risk factors, and vaccine prevention/therapy are also discussed, while acknowledging that the evidence for a causal association between MAP exposure and CM remains circumstantial.

Management of Mycobacterium avium subsp. paratuberculosis in dairy farms: Selection and evaluation of different DNA extraction methods from bovine and buffaloes milk and colostrum for the establishment of a safe colostrum farm bank

The aim of this study was to develop and validate different innovative DNA extraction methods to detect Mycobacterium avium subsp. paratuberculosis (MAP) DNA from bovine and buffalo colostrum. Paratuberculosis is a chronic inflammatory infection of domestic and wild animals, especially ruminants, caused by MAP. The primary route of disease transmission is feces, but MAP can also be excreted in milk and colostrum. In 2015, the Italian Ministry of Health has issued a voluntary control plan of MAP in order to allow risk‐based certification of bovine and buffaloes farms. In addition to the annual diagnostic screening and to the clinical surveillance of animals the plan includes the adoption of biosecurity and management measures to progressively mitigate the incidence of MAP. To achieve this goal it is crucial to ensure the accuracy of the methods used to detect the presence of MAP in bovine and buffaloes milk and colostrum, in order to: (1) support a "safe colostrum farm‐bank" set‐up and thus prevent the main within‐farm MAP transmission route and (2) to allow the MAP‐free certification of milk products for export purposes. To achieve these goals, seven different DNA extraction protocols were identified from bibliography, out of which three methods were finally selected after the adoption of an evaluation procedure aimed at assessing the efficiency of extraction of DNA, the purity of DNA and the adaptability of the DNA amplification: NucleoSpin^® Food Kit (Macherey‐Nagel), NucleoSpin^® Food Kit (Macherey‐Nagel) combined with the magnetic beads, and QIAamp Cador Pathogen Mini kit (QIAGEN). In particular, the NucleoSpin^® Food Kit (Macherey‐Nagel) and the QIAamp Cador Pathogen Mini kit (QIAGEN) were tested on bovine and buffalo colostrum, showing a LOD between 4 × 10⁴ (2.6 × 10⁶ cfu/ml) and 4.08 (26.7 cfu/ml) IS900 target copies and a LOD between 5.3 × 10⁵ (4.1 × 10⁶ cfu/ml) and 53 (4.1 × 10³ cfu/ml) IS900 target copies, respectively.

Mycobacterium avium ssp. paratuberculosis detection in animals, food, water and other sources or vehicles of human exposure: A scoping review of the existing evidence

Mycobacterium avium ssp. paratuberculosis is the etiologic agent of Johne's disease in ruminants and is hypothesized to be an infectious cause of Crohn's disease, as well as some other human diseases. Due to key knowledge gaps, the potential public health impact of M. paratuberculosis is unknown. This scoping review aims to identify and characterised the evidence on potential sources and vehicles of M. paratuberculosis exposure for humans to better understand how exposure is likely to occur. Evidence from 255 primary research papers is summarized; most examined the prevalence or concentration of M. paratuberculosis in animals (farmed domestic, pets and wildlife) (n=148), food for human consumption (62) (milk, dairy, meat, infant formula) or water (drinking and recreational) and the environment (farm, pasture and areas affected by runoff water) (20). The majority of this research has been published since 2000 (Figure- abstract). Nine case-control studies examining risk factors for Crohn's disease highlighted significant associations with the consumption of processed meats and cheese, while direct contact with ruminants, high risk occupations (farmer, veterinarian), milk consumption and water source were factors not associated with the disease and/or M. paratuberculosis exposure status. Molecular epidemiology studies demonstrated strain-sharing between species. Produce and seafood were the only previously suggested sources of human exposure for which there was no supporting evidence identified in this scoping review. The results of this review indicate that ruminant populations from around the globe are infected with M. paratuberculosis and many non-ruminant species have also been found to carry or be infected with M. paratuberculosis. Several potential sources for human exposure to M. paratuberculosis were identified; however there remain important gaps in quantitative information on the prevalence and concentration of M. paratuberculosis in contaminated sources of exposure. This information is critical to understanding the risk of exposure, opportunities for risk mitigation interventions and modelling exposures to distill the importance of various sources of human exposure to M. paratuberculosis including direct contact with animals and the environment as well as consumption of contaminated foods and water. Results of this study may be used to prioritize future research and to support evidence-informed decision-making on the M. paratuberculosis issue.

Facts, myths and hypotheses on the zoonotic nature of Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of paratuberculosis (Johne's disease [JD]), a chronic granulomatous enteritis in ruminants. JD is one of the most widespread bacterial diseases of domestic animals with significant economic impact. The histopathological picture of JD resembles that of Crohn's disease (CD), a human chronic inflammatory bowel disease of still unresolved aetiology. An aetiological relevance of MAP for CD has been proposed. This and the ambiguity of other published epidemiological findings raise the question whether MAP represents a zoonotic agent. In this review, we will discuss evidence that MAP has zoonotic capacity.

Inactivation of Mycobacterium avium subsp. paratuberculosis during cooking of hamburger patties

The role of Mycobacterium avium subsp. paratuberculosis (MAP) in Crohn's disease in humans has been debated for many years. Milk and milk products have been suggested as possible vectors for transmission since the beginning of this debate, whereas recent publications show that slaughtered cattle and their carcasses, meat, and organs can also serve as reservoirs for MAP transmission. The objective of this study was to generate heat-inactivation data for MAP during the cooking of hamburger patties. Hamburger patties of lean ground beef weighing 70 and 50 g were cooked for 6, 5, 4, 3, and 2 min, which were sterilized by irradiation and spiked with three different MAP strains at levels between 10² and 10⁶ CFU/ml. Single-sided cooking with one flip was applied, and the temperatures within the patties were recorded by seven thermocouples. Counting of the surviving bacteria was performed by direct plating onto Herrold's egg yolk medium and a three-vial most-probable-number method by using modified Dubos medium. There was considerable variability in temperature throughout the patties during frying. In addition, the log reduction in MAP numbers showed strong variations. In patties weighing 70 g, considerable bacterial reduction of 4 log or larger could only be achieved after 6 min of cooking. For all other cooking times, the bacterial reduction was less than 2 log. Patties weighing 50 g showed a 5-log or larger reduction after cooking times of 5 and 6 min. To determine the inactivation kinetics, a log-linear regression model was used, showing a constant decrease of MAP numbers over cooking time.

Survival of Mycobacterium avium subsp. paratuberculosis in synthetic human gastric juice and acidified porcine bile

The bactericidal activities of synthetic gastric juice and acidified porcine bile on Mycobacterium avium subsp. paratuberculosis were assessed using propidium monoazide (PMA)-mediated quantitative reverse transcription-PCR, which allowed rapid relative quantitative analysis of viable M. avium subsp. paratuberculosis cells.

Apparent Prevalence of Beef Carcasses Contaminated with Mycobacterium avium subsp. paratuberculosis Sampled from Danish Slaughter Cattle

Presence of Mycobacterium avium subsp. paratuberculosis (MAP) in beef has been reported as a public health concern because asymptomatically infected cattle may contain MAP in tissues that are used for human consumption. Associations between MAP carcasses contamination and animal characteristics such as age, breed, production type, and carcass classification were assessed. Cheek muscles from 501 carcasses were sampled cross-sectionally at a Danish abattoir and tested for presence of viable MAP and MAP DNA by bacterial culture and IS900 realtime PCR, respectively. Cheek muscle tissues from carcasses of two dairy cows were positive by culture whereas 4% of the animals were estimated with ≥10 CFU/gram muscle based on realtime PCR. Age was found to be associated with carcass contamination with MAP. The observed viable MAP prevalence in beef carcasses was low. However, detection of MAP and MAP DNA in muscle tissues suggested that bacteremia occurred in slaughtered cattle.

Mycobacterium avium subsp. paratuberculosis in dairy products, meat, and drinking water

Mycobacterium avium subsp. paratuberculosis (Map) is the cause of Johne's disease, a chronic infection of the gut, in ruminant animals that provide milk and/or meat for human consumption. Map also may be involved in Crohn's disease and type 1 diabetes in humans. Although the role of Map in human diseases has not been established, minimizing the exposure of humans to the organism is considered desirable as a precautionary measure. Infected animals can shed Map in feces and milk, and the organism can become disseminated in tissues remote from the gut and its associated lymph nodes. The presence of at least some Map in raw milk and meat and in natural waters is likely, but the numbers of Map in those foods and waters should be reduced through cooking or purification. The available information relating to Map in milk and dairy products, meats, and drinking water is reviewed here for assessment of the risks of exposure to Map from consumption of such foods and water.

Detection of Mycobacterium avium ssp. paratuberculosis in cheese, milk powder and milk using IS900 and f57-based qPCR assays

AIMS

To develop a quantitative PCR assay for sensitive and specific detection of Mycobacterium avium ssp. paratuberculosis (Map) in a range of dairy products.

METHODS AND RESULTS

TaqMan(®) assays were designed to target the IS900 and f57 genetic elements of Map. Both real-time PCR assays were integrated with the Adiapure(®) Map DNA extraction kit and assessed separately for the detection/quantification of Map in spiked milk, Cheddar cheese and milk powder. Assays were validated against Cheddar cheese samples containing known concentrations of Map. The IS900 qPCR assay was significantly more sensitive than the assay based on the f57 primer/probe. At a threshold cycle value of 38, limits of detection (LOD) for the IS900 qPCR assay were 0·6 CFU ml(-1), 2·8 CFU g(-1) and 30 CFU g(-1) for artificially contaminated pasteurized milk, whole milk powder and Cheddar cheese, respectively. The respective LOD's for the f57 assay were 6·2 CFU ml(-1), 26·7 CFU g(-1) and 316 CFU g(-1).

CONCLUSION

The integrated Adiapure(®) extraction - IS900 real time assay described is a sensitive, quantitative method for the detection of Map in dairy products. This is the first study to consider qPCR as a quantitative estimation of Map-DNA in cheese and whole milk powder.

SIGNIFICANCE AND IMPACT OF THE STUDY

The assay developed allows sensitive detection and quantification of Map DNA in a range of dairy products which is valuable for the screening and surveillance of this potential zoonotic organism.

Assessment of food as a source of exposure to Mycobacterium avium subspecies paratuberculosis (MAP)

The National Advisory Committee on Microbiological Criteria for Foods assessed the importance of food as a source of exposure to Mycobacterium avium subspecies paratuberculosis (MAP). MAP is the causative agent of Johne's disease, which affects primarily the small intestine of all ruminants. The significance of MAP as a human pathogen is unknown and is being investigated by several research groups. This document also reviews the efficacy of current detection methods, processing interventions, and MAP inactivation. Research needs related to MAP are provided. The Committee reached the following conclusions: current methods for detection of MAP have significant limitations, and a standard method for the detection of viable MAP cells is needed. Aside from MAP-infected domestic ruminant animals, the organism is found infrequently. If MAP in cattle is controlled, the source of MAP in other animals, food, and water may largely be eliminated. Milk, particularly raw milk, may be a likely food source for human exposure to MAP. Given the prevalence of MAP in U.S. cattle herds, ground beef may be a potential source of MAP. Although humans may be exposed to MAP through a variety of routes, including food and the environment, the frequency and amount of exposure will require additional research.

Contamination of food products with Mycobacterium avium paratuberculosis: a systematic review

Although a causal link between Mycobacterium avium subspecies paratuberculosis (MAP) and Crohn's disease has not been proved, previous studies suggest that the potential routes of human exposure to MAP should be investigated. We conducted a systematic review of literature concerning the likelihood of contamination of food products with MAP and the likely changes in the quantity of MAP in dairy and meat products along their respective production chains. Relevant data were extracted from 65 research papers and synthesized qualitatively. Although estimates of the prevalence of Johne's disease are scarce, particularly for non-dairy herds, the available data suggest that the likelihood of contamination of raw milk with MAP in most studied regions is substantial. The presence of MAP in raw and pasteurized milk has been the subject of several studies which show that pasteurized milk is not always MAP-free and that the effectiveness of pasteurization in inactivating MAP depends on the initial concentration of the agent in raw milk. The most recent studies indicated that beef can be contaminated with MAP via dissemination of the pathogen in the tissues of infected animals. Currently available data suggests that the likelihood of dairy and meat products being contaminated with MAP on retail sale should not be ignored.

Development and validation of a triplex real-time PCR for rapid detection and specific identification of M. avium sub sp. paratuberculosis in faecal samples

A triplex real-time (TRT-PCR) assay was developed to ensure a rapid and reliable detection of Mycobacterium avium subsp. paratuberculosis (Map) in faecal samples and to allow routine detection of Map in farmed livestock and wildlife species. The TRT-PCR assay was designed using IS900, ISMAP02 and f57 molecular targets. Specificity of TRT-PCR was first confirmed on a panel of control mycobacterial Map and non-Map strains and on faecal samples from Map-negative cows (n=35) and from Map-positive cows (n=20). The TRT-PCR assay was compared to direct examination after Ziehl-Neelsen (ZN) staining and to culture on 197 faecal samples collected serially from five calves experimentally exposed to Map over a 3-year period during the sub-clinical phase of the disease. The data showed a good agreement between culture and TRT-PCR (kappa score=0.63), with the TRT-PCR limit of detection of 2.5 x 10(2)microorganisms/g of faeces spiked with Map. ZN agreement with TRT-PCR was not good (kappa=0.02). Sequence analysis of IS900 amplicons from three single IS900 positive samples confirmed the true Map positivity of the samples. Highly specific IS900 amplification suggests therefore that each single IS900 positive sample from experimentally exposed animals was a true Map-positive specimen. In this controlled experimental setting, the TRT-PCT was rapid, specific and displayed a very high sensitivity for Map detection in faecal samples compared to conventional methods.